Those are my own opinions as to why. Plenty of people are working on those systems, so obviously there are plenty of people that have different opinion. They

Those are my own opinions as to why. Plenty of people are working on those systems, so obviously there are plenty of people that have different opinion. They are too big, and well established projects. I cant just plop down over a weekend and make some kind of meaningful contribution. Most of the low hanging fruit is already dealt with. Those are great systems to work with, or if you want to build on top of. Not that great if you just want to hack on core system. It's not that you can't because people definitively are. But expectations are bigger, scope is bigger, you need to keep multiple architectures in mind, people will use it on all kinds of hardware. You need to coordinate with dozens or more people. Everything takes more time.